With the world becoming more globalized and businesses interacting with each other on a daily basis, thanks to the Internet, global finance and international financial investments have become the standard for how businesses and countries do business. Two of the main reasons economists push for economic globalization are to reduce political barriers to trade and investment in the public sector and to reduce transportation and communication costs in the private sector (). One of the main ways that transportation and communication costs have decreased has been through technological improvements and advancements in recent years. The Internet has reduced communication costs from $244.65 to $3.32 from the early 1990s to today (). The world has undergone a great push. The most widespread risk is that these agents who are creating a financially globalized world could cause enormous financial crises. When the government liberalizes the country's financial system to enter other markets, it now comes through market discipline from domestic and foreign investors. Having domestic and foreign investors monitoring the country's economy can generate a crisis when fundamentals deteriorate (). Second, the possibility of imperfections in international financial markets can also lead to a crisis. It could generate speculative attacks, crashes, herd behavior and generate bubbles. This could happen if investors believe a country's exchange rate is unsustainable and speculate against that currency, leading to a self-fulfilling balance of payments crisis. Even with these agents in place, there are still barriers to a fully financially globalized world. One barrier that has been discussed recently is the existence of different currencies and the large fluctuation in exchange rates between them. Several tests have been conducted to see what effects a common currency would have on a country's economy. The gravity model (which removes one standard deviation in exchange rate variability from its mean of 7% to zero) shows that trade between two countries increases by 13% (). The test also showed that the FBI believes Bitcoin enables the transfer of illegal substances and other goods and is difficult to regulate. A clear example is the Silk Road, which was a black market for illegal drugs. The FBI seized $28.5 million in Bitcoin when it shut down the Silk Road last year. In December 2013, the Central Bank of China issued a warning about the risks of using Bitcoin and warned financial institutions not to deal with companies that use Bitcoin. Once this announcement was made, BTC China (the largest Bitcoin exchange in the world) stated that it would no longer accept yen deposits. This has affected investors around the world as bitcoin prices plummeted from $1,200 each to $500 today. Bitcoin has also seen opposition from economists like Paul Krugman and Brad DeLong who believe it is a flawed idea and question why it should act as a reasonably stable store of value or whether there is a floor on its value (). Others believe it acts as a threat to the Federal Reserve system and other central banks, but that it is a good thing because it allows them to operate in a healthy manner.